Advantages of Single tappping: -Most people find it easy to do
-Leads to more accurate taps
-You will react faster in tapping
Disadvantages of Single tapping: -Cannot overcome fast-paced maps
-Your fingers will be tired easily
-Not good at streams
Advantages of Alt tapping: -Good for streams
-Even distribution of your energy in your fingers, so you are not tired easily
-Fast-paced map will be a breeze
Disadvantages of Alt tapping: -The chances of mistapping a note is higher
-Most people find it weird
-Less accurate than Single tapping
Honestly, it is your own preferences, so keep up your playstyle and have fun playing!